U-lock



FIG. 1 is a prospective view of the U-lock design, the undisclosed opposite side being identical;

FIG. 2 is a front view of the U-lock design;

FIG. 3 is a side view of the U-lock design;

FIG. 4 is a bottom view of the U-lock design; and,

FIG. 5 is a top view of the U-lock design.

The phantom lines shown in the Figures are for illustrative purposes and form no part of the claimed invention. 

The ornamental design for a U-lock, as shown and described. 